It is all speculation because it doesn't matter. Pd used the years in which the film was coming out to theatres so it feels relevant upon release. No one can prove anything either way. I would rather believe the three years for the simple reason that I want batman to have been around longer before having been forced to retire. But there is evidence to disprove either version, so ultimately, take it as a full cohesive story - timeline is irrelevant.

My work is irrelevant, thanks. Don't worry, this is the last of my irrelevant that you will see.